


His Last Vow

by Dusty_Forgotten



Category: Sherlock (TV)
Genre: Alternate Universe - Canon Divergence, Alternate Universe - Serial Killers, Gen, Hallucinations, Implied/Referenced Self-Harm, M/M
Language: English
Status: Completed
Published: 2014-03-25
Updated: 2014-03-25
Packaged: 2018-01-17 00:39:06
Rating: Not Rated
Warnings: Graphic Depictions Of Violence
Chapters: 1
Words: 3,409
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/1367509
Author URL: https://archiveofourown.org/users/Dusty_Forgotten/pseuds/Dusty_Forgotten
Summary: <blockquote class="userstuff">
              <p>They always thought Sherlock was broken. They could never have imagined John being so much worse.</p>
            </blockquote>





	His Last Vow

No one knows.

Not even Sherlock knows, the kinds of things John is thinking. That's good. If he knew, he would try to suppress it for him, because Sherlock knows all about suppressing. He's been suppressing his own, for so much longer.

But Sherlock’s is so close to getting out. He's obsessing over Magnussen, so needy to get what he wants that he would _kill_ _for it..._

Just like John. In the war, of course, like “for Queen and country” was any part of John’s reasoning for enlisting. Like he was a normal person. Like he isn’t already bored out of his mind with wedding plans. Like he's on Baker Street for a valid reason, other than a prayer that Sherlock has a case, a client, anything to do. Instead, Holmes is so deep in his mind palace, he doesn’t notice John come in.

*

_“You’ll never catch Magnussen.”_

_“Why.” Sherlock asked, only a question by definition. He was demanding answers._

_“He’s better than you.” came Moriarty’s easy reply._

_“Why.”_

_Jim smiled slightly, in a way that Sherlock had never wanted to see again. He pulled himself up, and adjusted his suit jacket. “You’re not using your full potential.”_

_“How.”_

_The dead man raised his eyebrows in approval, smiling tight-lipped. “You’re holding yourself back.”_

_“How.” Sherlock interrogated. He was having trouble with all the subtleties he had to keep track of around (even his own construction of) Moriarty. He tried to be cold, put on the whole sociopath routine, but Jim knew him better than that. Knew him better than himself._

*

Sherlock snaps awake to a summons of his own name. He flicks his eyes over to John, standing by the coffee table with a plate in one hand, mug in the other. “This had better be important, John. I was nearly at a breakthrough.”

The doctor rolls his eyes, setting the plate on Sherlock’s stomach. Toast. “I know you don’t eat when you get like this.”

“I’m too busy to eat.”

“That’s why I made toast. Quicker and lighter than what you really should have. Eat, then you can get back to whatever it is you’re up to.”

He does. Sherlock is so used to having John around, he doesn't bother to ask why he's back. Sherlock finishes his food, and settles back into his mind palace.

*

_“You were saying?”_

_Jim shook his head, disappointed, before facing the wall and banging his head rhythmically into the padding. Sherlock scoffed, and left the room._

~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~

John is losing his mind, trying to tell the difference between four shades of the same colour for the nursery. _Isn’t this what he wanted?_

He knows it’s not; it’s what he forced on himself to maybe pretend he didn’t see murders every time he closed his eyes.

Then he gets woken up with the sun by a set of knocks on the door, and he nearly expects it to be Sherlock with a case, but it’s just the neighbour, Kate, with another sob story, nothing different from every other client he and Sherlock ever saw...

Well, a client is a client.

*

_“How do I catch Magnussen!?”_

_Moriarty didn’t bother sitting up, kept staring at the ceiling. “You’re asking the wrong questions. You’ll never catch him like this...”_

_Sherlock let out a breath. He had to finish this soon. “How do I reach my full potential?”_

_“Oh, Sherlock, there are still so many things you have to learn.”  With a grin, he pushed himself up with one arm, jingling the chain clasped around his neck, and wiped his dirty hand on his dirty T-shirt. “I like your mind palace. I wouldn’t make one for myself, though. So many walls. Too many rooms. Too easy to lock things away...”_

“Dr. Watson? ” darts into his brain, but he pushes it back out.

_One of the detective’s eyebrows quirked. “What am I hiding?”_

_Jim ran his fingers through his pomade-smoothed hair, which turned to havoc under his touch, and smiled, like one would smile at a joke they didn’t want anyone to know insulted them. “Me.”_

*

“Have you come for me?”

“Do you think I know many people here?”

Sherlock’s eyes flick open, and he rolls over. “Oh, hello John. Didn’t expect to see you here. Have you come for me, too?” He really wishes he had.

Watson looks mad, but oddly relieved, and that’s when Sherlock comes out of his self-loathing long enough to think that maybe John wasn’t such a suburban family-man after all. Then he just looks furious. Sherlock’s mad, because he didn’t ask John to save him, because he was so close to figuring out how to save himself. John is mad, because Sherlock isn’t ready to take him into war this time.

~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~

“Please, do relax. This is all for a case.”

And they argue again, like they've been arguing since Sherlock came back from the dead, and he can see that every angry word John throws back at him is a clever disguise for _See what I had to do while you were away?_ They keep arguing until the junkie breaks their attention.

“Somebody ‘it me.” he says, with an obvious glare at-

John shifts his eyes, and goes into a defensive stance, and the junkie doesn't push it, fear etched on him. “Probably just an addict. In need of a fix.”

Sherlock sees it, then: Afghanistan in his eyes, 221B in his veins, and no middle-class working husband anywhere underneath.

He knows how much John missed him.

~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~

_“You’re gonna love being dead, Sherlock. No one ever bothers you.”  Sherlock didn’t respond, just continued to fade in a heap on the floor as Jim mirrored him. “...Mrs. Hudson will cry, and, and mummy and daddy will cry, and The Woman will cry...” he said, standing, looking away, growing aloof, because he had always wanted Sherlock dead, right? “And John will cry, buckets and buckets. It’s him that I worry about the most. That wife...!”_

_He pretended not to look at him, didn’t connect, didn’t care, didn’t_ really _want Sherlock dead. “You’re letting him down, Sherlock. John Watson is definitely in danger...”_

 _That got him. Of course it did; Moriarty knew it would._ That’s why he said it. _“Oh, you’re not getting better, are you?” he goaded, because Sherlock had always loved proving him wrong. “Was it something I said, huh!? **SHERLOCK!** ”_

*

So Sherlock wakes up, because it's his only vow, and he's going to keep it. John is relieved, and Mary is scared, and Sherlock takes one to confront the other and takes them both back to the flat.

John’s chair is waiting for him.

~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~

John bought a knife a few days earlier. The gun was nice, but he knows he can't take it everywhere, especially being a “family man”, and all. Doesn't suit all his purposes, now.

It's a three inch flip-knife, serrated at the base. He keeps it in his pocket everywhere he goes. If he's alone, he might twiddle it. Play five-finger flay, like he used to with a combat knife in Afghanistan, like he used to with a scalpel before that. It used to be parlor trick.

If that doesn't do it, he puts a couple red lines in his arm. That helps.

Sherlock caught him at it once. Didn’t say anything. Doesn't say anything when the slashes add up, either, or human bits appear for him in the fridge, or John mutters to himself late at night and beats his head against the wall.

He thinks Sherlock doesn't care, because if the man is so good at deduction, why can't he deduce that his best friend is so close to gone?

It doesn't occur to him that Sherlock is too gone, himself.

*

_Sherlock breathed and leaned against the padded wall. It was so much more comfortable than he had imagined. Moriarty was whistling. “...You helped me.”_

_Jim stopped his sounds abruptly, looking up from where he sat by the detective’s feet. “So?”_

_“Why?” he asked, sliding to sit, side-by-side, with the man that wanted him dead not-so long ago._

_Jim looked at him, face dirty, hair ragged, so tired. “You’re all that’s left of me.”_

*

“Sherlock? What do you think?”

He realizes that his eyes had been open, and he's been staring at a prospective client for the past ten minutes. Holmes quickly assesses the man, finds him wholly uninteresting, and shoots John a look indicating such.

The doctor clears his throat, stands, and shakes hands with the man. “Yes, thank you. I’d take it to the Yard. Have a lovely day.” He shuffles the man out, and turns back to Sherlock. “You need a case.”

“I have a case.”

John rolls his neck like he does when he wants to snap at Sherlock, but decides against it, because he knows Sherlock knows best. “Magnussen isn’t a case.” he says tightly instead.

“He’s a difficult case, but a case. We’ve been hired, John.” Holmes steeples his fingers under his chin.

“Magnussen isn’t a case, he’s a villain. Just like Moriarty.” he chances, hoping to tick any kind of nerve, because at this point, a row would be better than the perfect _security_.

No response. John glances over his shoulder, like he does when he doesn't want to see Sherlock’s _infuriating face_ as the man stares into his own mind.

*

_Sherlock burst into the door; he was getting so tired of having to come back to this cell after being jolted out so many times. “You want to help me.”_

_Moriarty craned his neck back to look at the detective from where he lay on the floor. “You’re really losing it, Sherlock. I told you that already; it’s not a revelation.”_

_“No. You want to help me. You want to preserve this mind, because I am all that knows what you really are.”_

_Moriarty rolled his eyes and growled, loudly, phlegmy. “I told you that! C’mon, Sherly, I thought you were interesting...”_

_The consulting detective stepped forward, and stood with his toe pressed to Jim’s scalp. “I locked you in here because I thought you were dangerous, but you only want to help.”_

_Sherlock watched the way every muscle tensed under the straitjacket, teeth gritted, eyes locked into neutrality._ What took you so damn long? _“You’re losing your touch. Tell me something I don’t know.”_

 _The chains fell away, and the straps on his straitjacket unlatched, and everything just_ fit _. Sherlock grabbed the arm of the straitjacket, and pulled the smaller man to his feet. Moriarty faced the wall and shucked off the restraints, which fell to dust against the cement, and he ran his fingers through his hair, and stretched, and straightened his suit , and when he turned, he was Moriarty- truly, honestly, James Moriarty, consulting criminal, Reichenbach mastermind, Sherlock Holmes’s perfect enemy._

_“Where do we start?”_

*

Watson breathes heavily, an impossible weight in each inhale and exhale, like a tightening in his lungs that he can't relieve. It isn't that far off, when he thinks about it. White-picket paradise and a near-catatonic consulting detective is an anvil set squarely on his chest, _pressing_.

He tells the taxi to leave. He can't have any witnesses.

The light is on. He can see shadows, movement. Mary comes to the window by the sink, doing dishes. John can hear his pulse in his ears.

She sees him, standing silently, hands in coat pockets on the sidewalk. She forces a smile and raises a hand to wave. His phone goes off. He knows he has to answer it.

 

[Dec. 19, 10:24p.m.]

Breakthrough. Need you at 221B. -SH

John shoves the phone back away, next to the thumb drive he still hasn't checked. With as satisfying of a breath as he can manage, he balls his hands in his coat pockets and walks off. Brushing the knife there is comforting.

~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Sherlock is awake. Honestly, truly, wholly awake. John can see it, the way he looks at John, looks away from John, speaks to him, speaks to himself, speaks to someone else entirely. “You saw Mary?”

John begins  _How could you possibly know that?_ in his mind before he remembers this is Sherlock, and Sherlock is back. Of course Sherlock knows. “Yeah. Didn’t talk to her. Decided against it.

Sherlock rakes his eyes over him. _Goddammit, don’t deduce me please, can't let you **see**_ -. His eyes widen, brows tick up, and he smiles. “Glad I called.”

“So, ah, what’s this breakthrough you were on about?” he asks, trying to be nonchalant in changing the subject as he removes and hangs his coat. Naturally, Sherlock notices.

“Ah, yes. Sorry I’ve been, “absent”, but it’s paid off. When did you buy the knife, John?”

He blanches, forcefully breathes, and brushes the wrinkles from his coat where it hangs much longer than he needs to, to avoid facing Sherlock. “A-about a month ago.”

“That long?” he muses, watching as John sits across from him- he doesn’t have much of a choice. “How long have you been talking to Molly about this?”

“A-about what?” John spits, quickly; he can’t hesitate for these, or Sherlock will know. Like it's any use trying to hide something from the man, anyway.

“She didn’t tell me, John. You did. I appreciate the samples, but a jar of eyeballs in the fridge is like a psychopath’s rose bouquet. Where else would you get them? So, why would you go to Molly...?" He answers his own question, showoff. "She _is_ the only girl who knows you well, but not well enough, if, say, you need to need a little help dissecting your own psyche...”

John sets his jaw, straightening his back and breathes, _has to keep breathing..._ He can’t think of how to respond, but Sherlock doesn’t really need him to- never needs a response, just praise or a reality check. John needs that, too. “It won’t be much longer until we have Magnussen, now. Which reminds me, we’ve been invited to my parents’ for Christmas.”

~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~

_“Mycroft is too smart. He would know the punch was drugged.”_

_He didn’t have to search for him; Moriarty was free to roam his mind, now. “He wants Appledore almost as much as you want John back. Oh, but he could never allow you to take his laptop, big government job, and all. He’d appreciate it, though...” Moriarty suggested, filing his nails, feet up on the desk- Mycroft’s desk._

_“He can’t officially allow it.”_

_“Exactly. And that makes sure he’ll be quicker on the rescue. All settled.” the criminal determined, blowing on his nail. “That just leaves Johnny boy.”_

_“What about him?”_

_James tucked the file into the multitool, and switched to the knife. “You’re avoiding it because you don’t want to accept that there’s something wrong with him.” He tested the sharpness of it on his thumb._

_“Define “wrong”.” Sherlock defended, watching a prick of blood form on Jim’s fingertip._

_“Wrong as in, bloodthirsty adrenaline-junkie.” He tucked his thumb into his mouth, and removed it clean. “How are you going to handle that?”_

_"By letting him handle himself.”_

_Moriarty made eye contact, and jabbed the knife into the fine wood of Mycroft's desk. He replied, oddly calmly, “Fair enough.”_

~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~

John laughs indignantly. Sherlock was wrong. Horrendously, dangerously wrong. He is going to _kill_ Magnussen, because he won’t shut up about John’s newly-wife. His jaw clenches and unclenches quickly, trying to keep from gutting the man where he sits, because Sherlock must have a plan. He always has a plan. Sherlock knows best.

*

_He slams his hands down on the autopsy table where Molly would normally be, but everything’s moved around since he let Moriarty loose. “I was wrong!”_

_Moriarty turns from examining the corpse on the other table. “Were you? How disappointing. I really expected better from you, Sherlock.”_

_“There is no Appledore...”_

_“I know.” the consultant responds, leaning against the metal table. “I’m in your head, remember?”_ _Sherlock doesn’t look up. “C’mon, Sherl, it happens to everyone. Happened to me all the time. It’s why I’m_ dead _.” He pushes off that table, and leans on the one in front of him, mirroring Sherlock. “No one’s the wiser, though. I always made my mistakes look like my plans, and if that doesn’t work, you scrap the operation and kill all the witnesses.”_

_“I’m not killing John.”_

_“I wouldn’t ask you to. In his current state he’s more of an accomplice than a witness. It’s on you to make sure he doesn’t get caught.”_

_He nods, and straightens. Moriarty copies. “What do I do?”_

_“Poker face on. Don’t let ‘em know how hard this is hitting you.”_

_The detective breathes slowly. Outside, he doesn’t breathe at all. “Done.”_

_“Good. Now think. What do you know about Magnussen?”_

_Sherlock blinks, and they are in a dark room. Moriarty doesn’t seem to notice the change of scenery, or when Magnussen’s face lights up, magnified over his own. “Charles Augustus Magnussen. 1.92 metres tall, glasses of indeterminate use, born in-”_

_“BORING!” Moriarty shouted. The slide projected on him changed to a blank. “I don’t need you to tell me his bio when there's the Internet. Tell me what_ you _know about him.”_

_A picture of Magnussen in profile shrouded the criminal. “He has perfect recall, likely a photographic memory. He procures secrets, and uses them as blackmail. He asserts dominance by being as rude as possible, to prove he can.”_

_“There you are.” the shorter man said, turning to the screen where his own silhouette was cast. “How do you turn it on him?”_

_“There’s no way to fight for dominance; I have nothing to bargain with, now. His power is in his mind.”_

“Sherlock, do we have a plan?”

_“Bingo.” Jim said, turning back. His own picture lit up, a crime scene photo, bloody, at the Fall. “How do you turn his mind against him?”_

“Sherlock!”

_Moriarty whistled a descending scale. “Better hurry, there’s not much time. Options, now.”_

_“Can’t drug him.” Sherlock said, watching a projected video of John storm off. “Can’t frame or break him-”_

_“You’re out of time.” Moriarty snapped, seizing Sherlock by the shoulder and pushing him through the screen._

*

“I do so love your soldier face. I’d like to punch it. Bring it over here a minute.”

John glares at Sherlock, asking what to do. He can only nod; his options are gone.

_“He’s gonna kill him.” Moriarty mentions, beside Sherlock._

_“Magnussen or John?”_

_“John. Duh. I mean, look at him.”_   Magnussen flicks at the shorter man. _“His muscles all knotted, especially in the face- oh, now he’s goading him. Bad move, Magnussen.”_

_Sherlock’s eyes fall. “There’s nothing I can do. He’s won.”_

_“Eeeeeeeh.” Jim squeaks. “Yeah. Yeah, he has. Mycroft’s gonna be here any minute to arrest you, and Magnussen gets away clean. I wonder how long you’ll get. I wonder if they’ll let John off easy.” He shrugs. “Probably not.”_

“Sherlock.” John says with evident exasperation, less evident fury.

“Let him. I’m sorry, just... Let him.” His response is distant.

 _“You can hear him breathing now, can’t you? Angry. Angry little man, isn’t he? Oooh, he’s going to **murder** Magnussen. You’re the only thing holding him back.”_ Moriarty hints as the helicopters swoop in. _“...Why_ are _you holding him back?”_

Then, it hits him. “To clarify,” he asks, moving in next to his blogger, “Appledore vaults only exists in your mind, nowhere else? Just there.”

“They’re not real. They never have been.” Charles replies. The helicopter calls, and John begs for a plan, and Magnussen gloats. Moriarty stands next to the- not villain, as he currently explains- and just grins.

“Oh, do your research.” Sherlock says, snatching the gun from John’s pocket. He notices, but doesn’t fight, and Moriarty steps out of the way obligingly as Sherlock takes his place.

 _“ **SHOOT HIM!** ” _Moriarty screams.

“I’m not a hero, I’m a high-functioning sociopath. Merry Christmas!”

John flinches, but turns away, even before the shot, because he knows what's coming. Mycroft calls furious, terrified orders from the helicopter, and Sherlock warns his best and only friend off. Moriarty just laughs, gleefully, slapping his knees before covering his mouth to try and smother it.

Sherlock falls to his knees, defeated, while Jim moves into his view from John’s side. _“We’re not so different after all.”_ he says, moving to point of the SWAT team. He smiles up at the detective. _“See you soon, Sherl.”_ Only then does Holmes notice the murder weapon in his hand, before it goes into his mouth. _“Toodles!”_

_Bang._


End file.
